Diameter connection fresh air side of 82 mm (suitable for the included Alu-Flex hose) Expertise in dealing with electrical power and the applicable regulations is essential for installation. For usability and accuracy of fit, it is essential to note and compare the item description, the data provided and the item images in addition to the vehicle usage list. When making your evaluation, please note that you are evaluating our performance (period until your item is marked as shipped), not that of the post office. Customer satisfaction is our top priority, which is why we ask you to contact us before leaving a neutral or negative review. We always strive to solve problems to your complete satisfaction. If you have any questions about one of our products, we will be happy to advise you in det.